API翻译：glBindFramebuffer

Name

glBindFramebuffer
绑定一个named framebuffer object。

C Specification

void glBindFramebuffer( GLenum target,    GLuint framebuffer);

Parameters

target
指定framebuffer object要绑定的target。这个常量标识必须是GL_FRAMEBUFFER。

framebuffer
指定framebuffer object的名字。

Description

1.glBindFramebuffer让你创建或使用一个named framebuffer object。调用glBindFramebuffer，把target设为GL_FRAMEBUFFER，把framebuffer设为the name of the new framebuffer object，将绑定这个framebuffer object name。当一个framebuffer object被绑定，之前的绑定将自动断开。

2.Framebuffer object names是无符号整型。0值被保留，窗口系统用来提供默认framebuffer。Framebuffer object names和对应的framebuffer object contents被放置在当前GL rendering context的共享对象空间中。

3.You may use glGenFramebuffers to generate a set of new framebuffer object names.

4.当一个framebuffer object第一次被绑定时，它的3个关联点(GL_COLOR_ATTACHMENT0, GL_DEPTH_ATTACHMENT, and GL_STENCIL_ATTACHMENT) 的状态是GL_NONE。不太确定，上原文吧：The state of a framebuffer object immediately after it is first bound is three attachment points (GL_COLOR_ATTACHMENT0, GL_DEPTH_ATTACHMENT, and GL_STENCIL_ATTACHMENT) each with GL_NONE as the object type.

5.当一个非0的framebuffer object name被绑定，GL在target GL_FRAMEBUFFER的上的操作将影响绑定的framebuffer object，对target GL_FRAMEBUFFER的查询，或者framebuffer的细节如GL_DEPTH_BITS（从绑定的framebuffer object返回的状态）。当0值的framebuffer object name被绑定，作为初始状态，企图修改或查询target GL_FRAMEBUFFER的状态将会生成GL_INVALID_OPERATION错误。

6.当一个非零framebuffer object name被绑定，所有对这个framebuffer的渲染（with glDrawArrays and glDrawElements）和从这个framebuffer中读（with glReadPixels, glCopyTexImage2D, or glCopyTexSubImage2D），将使用关联到这个application-created framebuffer object的images，而不是默认的window-system-provided framebuffer.

7.应用程序创建的framebuffer objects不同于默认的窗口系统提供的framebuffer的几个方面。第一，他们拥有可更改的关联a color buffer, a depth buffer, and a stencil buffer的指向framebuffer attachable images的指针，这些images可以被attached and detached.第二，被关联的images的大小和格式，可以被GL完全控制，且不会被window-system事件影响，比如像素格式选择，窗口大小重置，和改变显示模式。第三，当对一个application created framebuffer object进行rendering to or reading，像素拥有权测试一直是成功 (i.e. they own all their pixels)。第四，没有可见的color buffer bitplanes，只有一个单一的”off-screen” color image attachment, 所以front and back buffers or swapping是没有意义的。最后，这里没有多重采样（multisample）buffer, 所以implementation-dependent state的值GL_SAMPLES and GL_SAMPLE_BUFFERS 都是0.

8.A framebuffer object binding created with glBindFramebuffer remains active until a different framebuffer object name is bound, or until the bound framebuffer object is deleted with glDeleteFramebuffers.

Notes

Queries of implementation-dependent pixel depths and related state are derived from the currently bound framebuffer object. These include GL_RED_BITS, GL_GREEN_BITS, GL_BLUE_BITS, GL_ALPHA_BITS, GL_DEPTH_BITS, GL_STENCIL_BITS, GL_IMPLEMENTATION_COLOR_READ_TYPE, GL_IMPLEMENTATION_COLOR_READ_FORMAT, GL_SAMPLES, and GL_SAMPLE_BUFFERS.